This invention relates to an incinerating system which advantageously utilizes normally wasted materials as fuel to produce heat energy without creating air pollution. In particular, the invention relates to an incinerator equipped with a heat exchanger, filtration means, and gas flow control devices, which combusts waste fuel, such as wood chips and shavings in a lumber mill, and recirculates the products of combustion to the incinerator for cooling and interior circulation. It extracts a maximum value of heat energy from the products of combustion with a minimal effect on the environment; either through release of pollutants or utilization of ambient air.
In industrial operations where waste product production is voluminous, such as in the lumber industry, the waste disposal problem is serious. Not only is it critically important to dispose of such wastes without injuring the environment, but it is also necessary to economically extract the energy content of the waste before disposal thereof so as not to squander a precious form of energy. Thus industry has long sought a system for concurrently extracting energy from waste, reducing the volume of the remainder thereof after combustion, and efficiently utilizing the energy obtained for useful purposes.
Attempts have been made to achieve these goals. The aforementioned United States patents to Drake, et al., disclose superior systems which efficiently consume waste materials and utilize the heated combustion products for useful purposes such as drying lumber, producing steam for the generation of electricity, and the like.
U.S. Pat. No. 3,945,331 describes an incinerator wherein the temperature of the exhaust products are controlled by the introduction of cold ambient air through a control valve. The patented system modulates the temperature of the exhaust products outside of the incinerator, i.e., to prepare the gases for a point of utilization.
U.S. Pat. No. 3,995,567 teaches a more advanced system wherein the exhaust gases are cooled and filtered to minute specifications before final release into the atmosphere. The system also includes a plurality of temperature controlled blowers in the incinerator walls for regulating the burning temperature of the fuel and for "after burning" particulate suspended in the exhaust from the primary burning area. Such "over fire" blowers direct ambient air to the interior of the incinerator and necessarily increase the mass gas flow of the system.
This invention is directed toward the achievement of an incinerating system which provides an efficient, low pollutant, burning of waste fuels to release heat energy without increasing the mass gas flow of the system despite the utilization of a variety of types and grades of fuel.